The ectodermal dysplasia syndromes are a group of genetic disorders which are identified by the absent or deficient function of derivatives of ectoderm (e.g. skin, nail, sweat glands or teeth). At least 150 different syndromes have been identified and it is estimated that the incidence of these disorders may be as high as 7 per 10,000 births. Two major subgroups of ectodermal dysplasias are hypohidrotic ectodermal dysplasia (HED) and hidrotic ectodermal dysplasia or Clouston syndrome (Ellis et al., 1980, Clin Exp Dermatol 5, 295–304; Pinheiro et al., 1994, Am J Med Genet 53, 153–162; Kere et al., 1997, U.S. Pat. No. 5,700,926).
Mutations in the human homolog of mouse dl have recently been reported to cause autosomal recessive and dominant hypohidrotic ectodermal dysplasia (Monreal, et al. 1999 Nature Gen 22, 366–369; Headon et al. 1999 Nature Gen 22, 370–374. We previously isolated a new member of the TNFR family, designated TAJ (originally, APO4, Chaudhary, 1999, WO9911791) and characterized its expression in embryonic and prostate tissue. Here we disclose that TAJ may be exploited for post and pre-natal diagnosis and treatment of ectodermal disorders such as Clouston syndrome.